1. Field of the Invention
The present invention concerns medical tourniquet devices for stabilizing and/or for inducing vasodilation of human veins in support of the venipuncture of or intravenous insertions into such veins.
2. Description of the Relevant Art
When in medical therapy or diagnosis it becomes necessary to puncture a human's blood vessel, nominally a vein, with a needle or syringe in order to inject medication, remove blood and/or make an intravenous connection, it is necessary to (i) locate a suitable vein and subsequently (ii) insert a needle through the skin (i.e. soft tissue) and into the interior of the vein. Sometimes during this procedure a suitable vein proves difficult to locate as well as often difficult to reliably insert the needle into its interior. Difficulties in location and/or insertion may exist because the walls of the patient's vein have degenerated at the site of venipuncture either from the effects of previous punctures because the patient is elderly or obese, and/or because the patient's vein is prone to roll from side to side. When a venipuncture is not reliably performed upon an initial attempt then it causes, at the minimum, additional discomfort and accumulative injury to the patient when the venipuncture is repeated. Unreliably performed venipuncture can also magnify and compound damage to the veins. Finally, unreliably performed venipuncture potentially results in poor intravenous connection for the collection of blood and/or the administration of therapeutic agents.
Devices for holding, stabilizing, constricting, immobilizing, and/or stimulating veins during medical venipuncture in order to aid the successful performance thereof are known in the prior art. U.S. Pat. No. 2,234,961 for a VEIN HOLDER to P. L. Canada shows a tourniquet in combination with a device for holding an adjacent vein against movement in order to facilitate intravenous injections and the like. The holding device comprises an arm of complex structure including a pressure member with fingers spaced to receive between them the vein which is to be punctured. Canada generally shows that a vein may be mechanically held not only against movement, but may also be held in high relief to aid medical personel in performing venipuncture.
U.S. Pat. No. 4,314,568 for VASCULAR STABILIZER to Loving shows an adjustable and disposable device maintained on a human appendage, and in pressured contact with the flesh about the location of a vein, by a strap. A living hinge portion connects two half body portions and permits a pivotal motion whereby ribs on each half-bodied portion may be brought together in parallel in order to stabilize a blood vessel lined between the ribs. A step locking mechanism prevents pivotal motion in a retrograde direction and thus ensures that the device is used for only a single venipuncture procedure, thereby preventing cross-contamination between patients. Loving generally shows that mechanical force may be used against the skin of a patient in order to draw a vein nearer to the surface of the skin.
U.S. Pat. No. 4,586,924 for VEIN CONSTRICTOR AND IMMOBILIZER for Lanning shows a device having a pressure plate which is hand held in pressured contact with the skin at the position of a vein. The planar pressure plate has in one of its ends a notch entirely through its thickness. At the apex of the notch a tapered groove is present within the bottom surface of the pressure plate. This tapered groove starts at the apex of the notch and terminates at the bottom surface of the pressure plate at a position intermediate the apex and the opposing edge of the pressure plate. When the groove and notch are both placed in pressured contact about the vein, they combinatorially constrict and immobilize the vein so as to allow venipuncture at the position of the notch. Lanning generally shows that veins may be mechanically constricted longitudinally, as well as laterally, along their length.
U.S. Pat. No. 4,316,461 for INTERVENOUS VASULAR STABILIZER to Marais, et al. discloses a method of performing venipuncture through a cutaway section within a central slot of a base plate, which slot overlays a vein. The slot is defined by an arched connector, or hood portion, which rigifies the slot and protects a needle-type catheder in its inserted positon. By exerting pressure on this connector, or hood, portion then the base is pressed downwardly on either side of the vein, which vein is then noticeably elevated into the slot area as well as being laterally stabilized. The pressure plate is held in position upon the human flesh and about the vein by straps. Marais, et al. generally shows that lateral pressure about a vein is useful for its mechanical stabilization during venipuncture.
Soft tissue in the area of veins may be mechanically manipulated other than in direct support of venipuncture. An example of the prior art showing mechanical manipulation of a vein at the site of venipuncture is contained within U.S. Pat. No. 3,620,209 for DEVICE FOR REDUCING THE PAIN OF INJECTIONS OF MEDICINES AND OTHER BILOGICALS to Kravitz. This patent shows a device which is held upon the skin, nominally by straps, and which vibrates the skin about the injection area. The vibration stimulates the pain center of the skin so that the pain of injections perceived by the patient may be minimized. Generally Kravitz indicates that stimuli, particularly taught to be mechanical stimuli, which is applied to the skin at or near the site of injection is potentially beneficial in mitigating or alleviating the patient's perception of pain associated with injection.
Also of relevance to the present invention is certain prior art concerned with the application of heated medical compresses to the skin, and the manner of generating heat externally or internally to such heated compresses. In this regard, U.S. Pat. No. 3,951,127 for CONSTANT TEMPERATURE DEVICE to Watson, et al., discloses a chemical heating device useable in medical applications. Specifically, a flexible container of a substantially planar configuration encloses a reservoir within which a first and second chemical may be combined in order to produce constant temperature heating. The resulting heated device is effected for use as a warm baby mattress, a warm blanket, or a hot water bottle substitute.
U.S. Pat. No. 3,463,161 for TEMPERATURE MAINTAINING DEVICE to Andrassy shows a flexible container containing a composition which is permanently plastic at temperatures throughout the range of zero degrees to one hundred and fifty degrees F. The container as well as its composition remains relatively soft and plastic during use. The container is generally divided into compartments by barriers and/or dividers. Andrassy generally shows that flexible containers which are useful in medical applications and which contain emulsions or dispersions may be readily fabricated.
U.S. Pat. No. 4,573,447 for CHEMICAL HEATER to Thrash, et al., discloses a chemical heater having a ruptureable container inside a substantially puncture- and rupture-proof envelope. After rupture of the inner container, heat is produced by exothermic reation. The particular chemical compositions, and the particular concentrations of chemicals within these compositions, which allow attainment of some desired exothermic reaction temperature are described.